High Capacity Mg Batteries Based on Inert and Non-Nucleophilic Carborane Electrolytes

在过去的十年里，可充电便携式设备和电动汽车的技术进步呈爆炸式增长。然而，降低成本、提高可持续性和增加最先进的锂离子技术所提供的存储容量的创新并没有跟上这场革命的步伐。此外，锂离子电池可能会发生灾难性故障，导致不可预测的火灾。镁基电池是锂离子系统的一个有吸引力的替代品，因为镁更便宜，更丰富，本质上更安全，并且可以存储两倍的电荷。 在材料研究部固态和材料化学项目的支持下，该项目将开发比传统锂离子系统更强大，更具成本效益的镁电池。 该项目的一个关键促成因素是实施由碳和硼原子集合组成的特殊电解质，称为碳硼烷。本科生和研究生在化学系在加州滨江（UCR）的大学是在这个程序的指导，并参与研究。此外，首席研究员（PI）和共同PI已将一个导师计划纳入该项目的弱势高中学生。在夏季的几个月里，这些高中生参加了UCR的拟议研究。 这些活动的预期结果是增加招聘和保留学生从代表性不足的群体在STEM领域。技术摘要镁基电池是一个有吸引力的替代锂离子系统，但缺乏合适的电解质。用于镁电池的电解质必须完全抗分解，并且理想地是非亲核的。该项目的目标是生产比最先进的锂离子技术更便宜、更安全、更可持续和更强大的镁基电池。这项工作的一个关键特征是实现惰性和非亲核的碳硼烷基电解质，这将使高容量镁电池的实现。该项目将通过三个具体目标来实现。目的1利用新的化学还原方法制备简单的双阳离子镁碳硼烷盐的无卤电解质。因为碳硼烷阴离子是高度氧化稳定的且非亲核的，所以它们适合用作利用高电压嵌入或S阴极的系统的Mg电池电解质。目标2包括设计具有支持配体的单阳离子碳硼烷电解质。实施新的transmetalation方法允许获得含有碳硼烷抗衡阴离子的单阳离子镁络合物，其是用于高电压嵌入阴极的合适电解质。此外，制备硫兼容的“钝化”电解质衍生的N-杂环卡宾（NHC）与S8的反应正在调查中。在目标3中，将目标1和2中制备的电解质与合适的阴极材料偶联以生产原型可再充电Mg电池。 层状钼和钒的硫化物以及硫尖晶石钒和铬的硫化物都用作嵌入型阴极。此外，基于具有两种类型的具有明显不同孔径的碳主体的硫-碳复合物的硫阴极正在研究中。

Non-Technical AbstractOver the last decade there has been an explosion of technological advances in rechargeable portable devices and electric vehicles. However, innovations that reduce the cost, improve the sustainability, and increase the storage capacity offered by state-of-the-art Li-ion technology have not kept pace with this revolution. In addition, Li-ion batteries can undergo catastrophic failure, which results in unpredictable fires. Mg-based batteries are an attractive alternative to Li-ion systems because Mg is less expensive, much more abundant, inherently safer, and can store twice the amount of charge. With the support from the Solid State and Materials Chemistry program in the Division of Materials Research, this project will develop Mg-batteries that are more powerful and cost effective than traditional Li-ion systems. A key enabling factor of this project is the implementation of special electrolytes composed of collections of carbon and boron atoms called carboranes. Undergraduate and graduate students in the Chemistry Department at the University of California Riverside (UCR) are mentored in this program and participate in research. Additionally, the Principal Investigator (PI) and Co-PI have integrated a mentorship program into the project for disadvantaged high school students. In the summer months, these high school students participate in the proposed research at UCR. The anticipated outcome of these activities is the increased recruitment and retention of students from underrepresented groups in STEM fields.Technical AbstractMg-based batteries are an attractive alternative to Li-ion systems, but suitable electrolytes are lacking. Electrolytes for Mg batteries must be completely resistant to decomposition and ideally non-nucleophilic. The goal of this project is to produce Mg-based batteries that are less expensive, inherently safer, more sustainable and powerful than state-of-the-art-Li-ion technology. A key feature of this work is implementing inert and non-nucleophilic carborane based electrolytes, which will enable the realization of high capacity Mg-batteries. This project will be accomplished via three specific aims. Aim 1 utilizes novel chemical reduction methodology to prepare halide free electrolytes of simple dicationic Mg carborane salts. Because the carborane anions are both highly oxidatively stable and non-nucleophilic, they are suitable for applications as Mg battery electrolytes for systems that utilize either high voltage intercalation or S cathodes. Aim 2 encompasses the design of monocationic carborane electrolytes featuring supporting ligands. Implementation of novel transmetalation methodology allows access to monocationic Mg complexes that contain carborane counter anions, which are suitable electrolytes for high voltage intercalation cathodes. In addition, the preparation of sulfur compatible "passivated" electrolytes derived from the reaction of N-Heterocyclic Carbenes (NHCs) with S8 is under investigation. In Aim 3, the electrolytes prepared in Aims 1 and 2 are coupled with suitable cathode materials to produce prototype rechargeable Mg-batteries. Both layered molybdenum and vanadium sulfides as well as thiospinel vanadium and chromium sulfides are utilized as intercalation type cathodes. In addition, sulfur cathodes based on sulfur-carbon composites with two types of carbon hosts having distinctly different pore sizes are under investigation.